RV Hydronic Heater Repair




This model may also be known as:


AHE-600-DE2, 600-D

This model of Aqua-Hot uses the special Camco -100 Boiler coolant.




Changes From Previous Model


  This is the first model in the 600-D series that is "Low Emissions" model
      and is a major redesign of the previous model


  • Low emissions model
  • NO RADIATOR cap - Zero pressure system
  • Has drain valve on short length of heater hose
  • Mixing valve is in different location (inside compartment to the right top of Webasto)
  • Fuel connections are now on the top of unit, above pumps
  • Engine preheat connections are on top of unit, above pumps
  • Recommended exhaust pipe is 2" ID (up from 1 5/8")
  • Has case interlock switch that will not allow burner to run until switch is depressed
  • High limit thermostats are now set to trip at 215° (up from 220°)
  • Some heaters in this series have tank liquid SENSOR in place of the mechanical float switch.  This tank level sensor is no longer available, see replacement below.
  • Coolant lines check valves are now mounted horizontally
  • Fuel lines are solid metal (no rubber hoses)
  • Aqua-Hot is installed in a 'tray' that is installed first.  Aqua-Hot is then mounted in coach using this tray.
  • Has white fiber gasket installed between combustion chamber (that is bolted in) and Aqua-Hot.


Part Notes


  • Control Thermostat -   ELE-014-010
  • Electric high limit thermostat - ELE-000-616-FRU
  • DUAL Diesel high limit thermostat - Thermostats are wired in series.  If one trips, the burner will shut down / not light   ELE-HLT-425
  • Control Board -  ELE-PC4-010
  • Electric relay(s) - ELE-630-001
  • Tank level sensor - This is the upgrade sensor  ELE-800-006-FRU
  • Zone and engine preheat pumps (are no longer available).  Pump upgrade kit, here: PLE-100-905-FRU
  • Gasket that goes between the combustion chamber and the Aqua-Hot   HDE-700-205
  • This model uses the special GRAS (generally recognized as safe), Camco -100 Boiler coolant.



Routine service parts and kits - Routine Service Parts      Scroll down page for filter and nozzle packages.  You should have the fiber gasket on hand in case you take the combustion chamber out.  HDE-700-205


Routine service note:  The Aqua-Hot service directions clearly state that the combustion chamber should be removed each time unit is serviced.  Most of the service people that I know remove the air swirler as shown in photo below.  They Inspect the inside of combustion chamber with flashlight.  If there is very minimal carbon built up (which they find in most instances), they do not remove the combustion chamber.

Common Problems


   None that I know of.

Service Manual


On Aqua-Hot website   AHE-600-D02